Dear Guix,

I changed the calibre recipe to accomodate for the changes for 3.0.0.
In the process I replaced one of the patches that removed the external
links to favicons with a substitution.  (The patch wouldn't apply
anymore).

So, the following patch updates calibre to 3.0.0.  I tested that it
works and that I can copy books to my e-reader.  .. And of course that
works fine.

Kind regards,
Roel Janssen